Former Cabinet ministers and lawmakers involved in gift and money scandals apologized again Monday as they returned to the Diet for its ordinary session, but offered no new details despite mounting calls for them to explain themselves.

"I feel deeply sorry for harming public trust in politics," former Justice Minister Katsuyuki Kawai told reporters as the regular Diet session started. "I should refrain from comment as investigations are underway."

Kawai and his wife, Upper House lawmaker Anri Kawai, both from the ruling Liberal Democratic Party, have faced allegations that they were involved in daily allowance payments by her office to campaign staffers for the July Upper House election that exceeded their legal limit.